(a) Visible emissions. No person may cause, suffer, allow, or permit visible emissions from any source, except as follows.
  (1) Stationary vents. Visible emissions from any vent shall not exceed the following opacities and must meet the following requirements.
    (A) Opacity shall not exceed 30% averaged over a six-minute period.
    (B) Opacity shall not exceed 20% averaged over a six-minute period for any source on which construction was begun after January 31, 1972.
    (C) Opacity shall not exceed 15% averaged over a six-minute period for any source having a total flow rate greater than or equal to 100,000 actual cubic feet per minute, unless an optical instrument capable of measuring the opacity of emissions is installed in the vent in accordance with subparagraph (D) of this paragraph. Facilities utilizing such instruments shall meet opacity limits outlined in subparagraph (A) or (B) of this paragraph as applicable. Records of all such measurements shall be retained as provided for in §101.8 of this title (relating to Sampling).
    (D) Any opacity monitoring system installed as provided for in subparagraph (C) of this paragraph must satisfy the new source performance standards requirement for opacity continuous emissions monitoring systems (CEMS) as contained in 40 Code of Federal Regulations (CFR) Part 60, Appendix B, Performance Specification 1. In order to demonstrate compliance with Performance Specification 1, the system shall undergo performance specification testing as outlined in 40 CFR 60.13. The facility will maintain records of all such testing for a period of not less than two years which shall be available for inspection by federal, state, and local air pollution control agencies. Compliance with this provision shall be accomplished within one year of the effective date of this rule, except as specified in paragraph (2) of this subsection.
    (E) Visible emissions during the cleaning of a firebox or the building of a new fire, soot blowing, equipment changes, ash removal, and rapping of precipitators may exceed the limits set forth in this section for a period aggregating not more than six minutes in any 60 consecutive minutes, nor more than six hours in any 10-day period. This exemption shall not apply to the emissions mass rate standard, as outlined in §111.151(a) of this title (relating to Allowable Emissions Limits).
    (F) Compliance with subparagraphs (A)-(C) of this paragraph shall be determined by applying the following test methods, as appropriate. The highest reading obtained shall determine compliance with the appropriate visible emission limit:
      (i) CEMS as described in subparagraph (D) of this paragraph;
      (ii) Test Method 9 (40 CFR 60, Appendix A);
      (iii) Alternate Method 1 to Method 9, Light Detection and Ranging (40 CFR 60, Appendix A); or
      (iv) equivalent test method approved by the executive director of the Texas Air Control Board (TACB) and United States Environmental Protection Agency (EPA).
    (G) Current certification of opacity readers for determining opacities under 40 CFR 60, Appendix A, Method 9, shall be accomplished by the successful completion of a TACB visible emissions evaluator's course by opacity readers no more than 180 days before the opacity reading.
  (2) Sources requiring continuous emissions monitoring. Beginning March 1, 1994, all stationary vents located at the sources specified in this paragraph shall be equipped with a calibrated and properly operating CEMS for opacity. The system shall be calibrated, installed, operated, and maintained as specified in 40 CFR 51, Appendix P, hereby incorporated by reference:
    (A) steam generators fired by solid fossil fuel with an annual average capacity factor of greater than 30%, as reported to the Federal Power Commission for calendar year 1974, and with a heat input of greater than 250 million British thermal unit per hour;
    (B) steam generators that burn oil or a mixture of oil and gas and are not able to comply with the applicable particulate matter and opacity regulations without the use of particulate matter collection equipment, and have been found to be in violation of any visible emission standard contained in a state implementation plan;
    (C) catalyst regenerators for fluid bed catalytic cracking units of greater than 20,000 barrels per day of total feed capacity.
  (3) Exemptions from continuous emissions monitoring requirements. Opacity monitors shall not be installed or used to determine opacity from any gas stream or portion of a gas stream containing condensed water vapor which could interfere with proper instrument operation, as determined by the executive director. Opacity monitoring techniques as listed in paragraph (1)(F) of this subsection may be substituted with the approval of the executive director and EPA, the highest reading of which will be used to determine compliance with the appropriate opacity standard. If opacity is determined through 40 CFR 60, Appendix A, Method 9, readings shall be made daily, unless weather or other conditions prevent visual observation.
  (4) Gas flares.
    (A) Visible emissions from a process gas flare shall not be permitted for more than five minutes in any two-hour period, except as provided in §101.11(a) of this title (relating to Exemptions from Rules and Regulations). Process gas flares are those used in routine or scheduled facility operations. Acid gas flares, as defined in §101.1 of this title (relating to Definitions), are subject only to the provisions of paragraph (1) of this subsection. Beginning September 1, 1993, compliance with this subparagraph for process gas flares shall be determined:
      (i) any time there is an operational change in the flare that requires a permit amendment under TACB Regulation VI. Compliance shall be determined using Reference Method 22 (40 CFR 60, Appendix A), Reference Method 9 (40 CFR 60, Appendix A), or an alternative test method approved by the executive director and the United States Environmental Protection Agency (EPA). The observation period for this compliance demonstration shall be no less than two hours unless noncompliance is determined in a shorter time period or operational changes are made to the flare that stop any observed smoking; and
      (ii) by a daily notation in the flare operation log that the flare was observed including the time of day and whether or not the flare was smoking. For flares operated less frequently than daily, the observation will be made for each operation. The flare operator shall record at least 98% of these required observations. If smoking is detected, compliance with the emission limits of this paragraph shall be determined using Reference Method 22, Reference Method 9, or an alternative test method approved by the executive director and EPA. The observation period for this compliance determination shall be no less than two hours unless noncompliance is determined in a shorter time period or operational changes are made to the flare that stop the smoking. A Method 22 or Method 9 observation will be waived provided the operator reports the flare to be in an upset condition under the requirements of §101.6 of this title (relating to Notification Requirements for Major Upset).
    (B) Flares used only during emergency or upset conditions are exempt from the compliance monitoring requirements of subparagraph (A)(i) and (ii) of this paragraph.
  (5) Motor vehicles. Motor vehicles shall not have visible exhaust emissions for more than 10 consecutive seconds. Compliance shall be determined as specified in 40 CFR 60, Appendix A, Method 22.
  (6) Railroad locomotives or ships.
    (A) Visible emissions shall not be permitted from any railroad locomotive, ship, or any other vessel to exceed an opacity of 30% for any five-minute period, except during reasonable periods of engine start-up.
    (B) Compliance with subparagraph (A) of this paragraph shall be determined by applying the following test methods, as appropriate:
      (i) Test Method 9 (40 CFR 60, Appendix A); or
      (ii) equivalent test method approved by the executive director and EPA.
  (7) Structures.
    (A) Visible emissions shall not be permitted to exceed an opacity of 30% for any six-minute period from any building, enclosed facility, or other structure.
    (B) Compliance with subparagraph (A) of this paragraph shall be determined by applying the following test methods, as appropriate:
      (i) Test Method 9 (40 CFR 60, Appendix A); or
      (ii) equivalent test method approved by the executive director and EPA.
  (8) Other sources.
    (A) Visible emissions shall not be permitted to exceed an opacity of 30% for any six-minute period from all other sources not specified in this section.
    (B) Compliance with subparagraph (A) of this paragraph shall be determined by applying the following test methods, as appropriate:
      (i) Test Method 9 (40 CFR 60, Appendix A); or
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